German firemen rescued a mysteriously naked man trapped in a narrow chimney in central Berlin, a spokesman said on Thursday.

The fire brigade was alerted to the emergency after police failed to help the 39-year old man who was wedged 10 meters (yards) down the shoulder-width chimney.

"The rescue workers, specialized in saving people at great heights, tried to pull the victim out from above with a crane and a sling," a fire brigade spokesman said.

"At first he held on to the rope but then his strength failed him so we had to come up with an alternative."

The team of about 30 firemen and 10 police officers bored a hole in the second floor of the building and managed to pull out the victim but not before he had lost consciousness. He needed 15 minutes of resuscitation and is still in hospital.

"He suffered from injuries in the fall and due to his scant clothing - namely his nakedness - he became very cold," the spokesman said.

The rescue operation took just under two hours but it is unclear how long the man had been in the chimney before police were first alerted to his cries of distress.

It is not known what the man was doing on the roof. Some media reports said he was homeless and escaped from a hospital.

"The first question was is the man sporting a red cape and a bushy white beard?" the fire brigade spokesman said.